build: remove hads document server

[rhopman]

Description

Proposal to remove hads, a document server that seems to be abandoned and has dependencies with vulnerabilities.

Personally, I don't see a need for a document server in the project, but if other people do we should look for one that is actively maintained.

Removing hads instantly resolves 5 high and 2 moderate vulnerabilities.

Checklist

Please make sure these boxes are checked before submitting your pull request - thanks!

• If you have multiple commits please combine them into one commit by squashing them.

• Read and understood the contribution guidelines at web-app/.github/CONTRIBUTING.md.

[rhopman]

I had to add @fortawesome/fontawesome-free (version 6), since hads had a dependency on font-awesome (version 4) that was actually used in the application. For backward compatibility with version 4, node_modules/@fortawesome/fontawesome-free/css/v4-shims.css is added to angular.json.